Some brains remain preserved for millennia, here is their secret

A new study has compiled data from archaeological literature on human brains dating back centuries. This study, published earlier this year, in March 2024, and spotted by Scientific American on December 2, is the largest carried out to date. It was led by Alexandra L. Morton-Hayward of the University of Oxford.

The scientist collected and analyzed data from more than 4,400 brains from hundreds of different sources on every continent (except Antarctica). Several of them were 12,000 years old and in 1,300 cases the brain was the only organ preserved from the remains.

The brain is perishable

However, the brain is one of the most perishable organs in our body and it is normally impossible for it to be preserved naturally for millennia, unless there are special weather conditions. It is even rarer that it is the only organ to be preserved in a skeleton. At least, that’s what researchers thought until now. This new study demonstrates that this phenomenon is less rare than it seems.

In 2008, archaeologists discovered in England the remains of a 2,500-year-old man who was likely to have been hanged, decapitated and thrown into an irrigation canal. Surprisingly, his brain remained partially intact. In 2020, scientists from University College London chemically studied this brain and discovered around 800 preserved proteins there.

One of the theories put forward to explain the survival of these thousand-year-old brains, in addition to particular weather conditions, involves a biochemical mechanism: the misfolding of proteins, which leads to the formation of aggregates.

Sick among the living, preserved among the dead

“In the forensic field, it is well known that the brain is one of the first organs to decompose after death — but this enormous archive clearly demonstrates that there are certain circumstances in which it survives. Whether these circumstances are environmental or related to the unique biochemistry of the brain is the focus of our current and future work. We find an astonishing number and types of ancient biomolecules preserved in these archaeological brains, and it’s exciting to explore how much they can tell us about life and death among our ancestors. “, says Alexandra Morton-Hayward in a press release from the University of Oxford.

To be able to play their role correctly, the proteins in our body must acquire a particular shape. Sometimes, for various reasons, a protein can misfold and then become tangled, accumulating, and forming a small group with other misfolded proteins. These are called aggregates. In living people, these protein aggregates in the brain are the cause of numerous diseases such as Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis (ALS). However, in the dead, it is the formation of aggregates which allows, at least in part, the preservation of the brain for centuries.

« These ancient brains provide an important opportunity to gain unique insight into the early evolution of our species, such as the roles of ancient diseases “, says Dr. Ross Anderson, co-author of the study. Probably sick brains, therefore, but which, at least, will have had the privilege of surviving the ages.